When worlds collide
by son-goku5
Summary: My attempt at a crossover of these two universes. I know, the title sucks. Strictly a one-shot. Read and Review please :)


**So, a reader asked me to think about a crossover of Castle and TBBT. This is the attempt to do it ^^**

 **As for the timeline of each show: TBBT is in its ninth season, Lenny are married and Castle is in its seventh season. Caskett is married as well but Gates is still around (and because I hate the 'I lie to everyone again, even my husband, to take down a supercriminal' storyline although they have remedied it now somewhat with Kate coming clean to Rick)**

 **By the way, for my Castle story, I created a character of my own for several of the chapters that seemed to have become somewhat popular. While I won't bring him in here, I will allude to him.**

 **Hope you enjoy :)**

 **Disclaimer: No character belongs to me, they belong to those who created them.**

* * *

"I still think that announcing your idea was a bit premature." Leonard cautioned, trying to stay calm while the man opposite of him was quite agitated.

"No, don't you see?" Ignaz Holtzmann, the man that Leonard argued with, returned. "By revealing my intentions, I can open up funding and therefore finish it quicker."

"But quicker doesn't equate better, why not work on it half a year longer rather than making a mistake and causing you to become ridiculed. Not to mention the ammunition it gives to the politicians who are already trying to shut you down." Leonard explained.

"Why do these guys try to stop you anyway?" Penny asked, wondering about that since she heard about it.

"They get bribes from the fossil fuel industry of course." Ignaz told her forcefully, his arms flailing, which seemed to be an eastern european habit when talking excitedly. "Although, here in the US they call it campaign contributions, so they are pretty much legal as long as you don't ask for the favor when you fork over the money."

"Still, I still think it was too soon." Leonard brought them back to topic. "You should have waited until you have at least a working prototype."

"I still don't know what exactly you are building down there." Penny said to Ignaz.

"It's an engine that only runs on water. It doesn't even have to be deionized water, you can pour any liquid in there as long as the filter can process it. It's small enough to fit into a car, or any other type of transport vehicle. Imagine a world where no car, no plane, no ship or what have you runs on gasoline or a nuclear reactor anymore. Think what it would mean for the planet in terms of climate change."

"I understand." Penny nodded. "I think."

"But even if you make a car engine, we don't have the means to produce the amount of either filters or deionized water we would need to fuel all those cars." Leonard argued.

"True, but that is an industry that would take care of itself once the technology is out there."

"I hope you are right." Leonard sighed. "You might want to start by offering that engine to the military for their ships. A fleet of ships that can basically refuel itself while on water is a welcome prospect and it could protect you from your critics if it's working."

"I will let you get back to your audience." Ignaz said. "Come by my lab when you are done here and maybe we can get a bit further along until you leave for California again."

"Thanks, Ignaz." Leonard shook the man's hands. "Good luck."

"What's that about the fuel?" Penny asked Leonard.

"To power a engine like his, you need clean water, and the cleaner the water is, the better it is for the longevity of the filter. There are already production facilities since deionized water also needed for car batteries but they don't produce enough to feed the world." he replied.

"Let me guess, making that stuff costs a lot of energy and water."

"Yes. Cleaning water is energy hungry and produces a lot of waste."

"Alright then. And how much longer do I have to be bored?" Penny asked with a grin.

"Two more hours at least, I'm afraid." Leonard grinned. "Too many of those people want to ask me questions."

"Those are the days when I really regret having said I do at our wedding." she huffed mockingly and grabbed her kindle to continue reading.

"I love you too." he said smiling and pressed a kiss to her temple before getting out to face the crowd again.

* * *

"Lanie, what do we have?" Kate asked as she entered the laboratory with Rick behind her, seeing the medical examiner bent over the victim.

"Victim is Ignaz Holtzmann, resident Professor of physics and engineering here at Columbia." Lanie replied.

"Cause and time of death?" Kate asked.

"I have no idea what could have done it but I think the round five inch hole where his heart used to be is the cause of death." Lanie told her, a little flippant. "Lividity puts time of death at between one and three pm."

"He was shot by a laser!" Rick stated excited, sure of the fact.

"How do you figure?" Esposito asked, standing on the other side of the lab.

"There's almost no blood. A wound like this would make his blood to leak out even without the heart pumping it." Rick told the latino detective. "Also, the wound is cauterized, which only happens with extreme heat."

"Writer-boy is correct." Lanie nodded. "Also, there are scorch marks on his clothes where the beam hit him. Plus, that laser had to have burned through him so fast that it didn't set his clothes on fire."

"But there's no laser that could kill him like this." Rick mused.

"Really?" Kate lifted her eyebrows. "Remember that case at SuperNovaCon? The guy built two phaser pistols that could kill."

"Yes, but the beam and the wound were maybe a few millimeters wide. This one is massive compared to that." Rick argued. "I don't know of any technology that could create a laser beam this wide that could still kill."

"Guys, start canvasing the area and try to dig up anything about our victim. Maybe something he worked on made him enemies." Kate ordered as Rick began surfing the internet with his phone.

"I think we may already have one." Rick proclaimed and showed her the screen where they watched a Youtube video of their victim apparently arguing heatedly with a short bespectacled man and a blond woman next to both of them.

"The video is only three hours old." Kate said, seeing the time stamp. "Try to find out who those other two are, maybe they know something or maybe they even had a hand in it."

"I think we can ask him right now." Ryan spoke up and pointed to the door.

"What's going on here?" Leonard asked upon entering.

"Oh god!" Penny yelled and ran to the sink, throwing up into it after seeing the corpse on the floor.

"Oh crap." Leonard winced and turned away, feeling nauseous but managing not to vomit.

"Who are you?" Kate asked.

"I'm Doctor Leonard Hofstadter." Leonard replied and pointed to Penny. "This is my wife Penny."

"Good. You are under arrest for the murder of Ignaz Holtzmann." Kate proclaimed, mentioning to Ryan to cuff him.

"No, I'm not." Leonard stated calmly and walked to Penny to caress her back and hand her a tissue.

"When she says you are, then you are." Rick threw in, surprised at the man's calm.

"Listen, I will come with you to your precinct if I have to and answer your questions but I won't have you bring me out of this building in handcuffs when I'm obviously innocent."

"You were filmed arguing pretty heatedly with the victim." Kate stated, pointing to Rick to show Leonard the Youtube video.

"That wasn't an argument." Leonard returned. "Even if it were, is arguing with someone always a reason for killing him?"

"I don't know, you tell me." Kate said.

"Are you alright Penny?" Leonard asked his wife, ignoring the police for now.

"No, can we get out of here? The smell is killing me." she replied.

They moved out of the lab and into the open air, followed by some uniforms who made sure that they didn't make a run for it and waited for the detectives to come out. After several minutes of just holding each other, the rest of the police force returned, the medical examiner team pushing the stretcher with the body bag on it, making Leonard look away sad at the death of his friend.

"Would you please get into my car?" Kate asked, pointing to her crown vic.

Leonard and Penny nodded and got into the backseat of the car while the detective and her male partner, which looked somewhat familiar to Penny, got into the front seats. They drove through the New York traffic until they reached the precinct and got out, walking into the building and taking the elevator up to the fourth floor to the homicide department.

Leonard led Penny into the conference room where she sat down and he handed her a cup of water he had gotten from the water cooler. She smiled sweetly at him and drank the cool liquid, finally washing the taste of her vomit out of her mouth. While they waited for the detective to come ask them something, they mulled over the events of the last thirty minutes.

"I can't believe he's dead." Leonard sighed.

"Who would do such a thing?" Penny asked.

"Well, there are some people who I can think of." Leonard shrugged. "Basically the entire leadership of the fossil fuel industry."

"What about the governments of oil countries?" she asked.

"Unlikely. While I don't believe that they are above having someone killed, they would still have their customers since you need oil for basically everything from plastic, lubricants, fertilizers or cosmetics."

"How much oil is used for transportation?"

"I think between seventy and eighty percent, why?" he replied.

"Well, if I ran a country whose income is solely or in large parts based on me selling oil to the world, the prospect of losing eighty percent of the demand for my product could lead me to take drastic actions."

"Never thought of that." he mused, as the door opened and the female detective entered with her partner.

"Doctor and Misses Hofstadter, my name is Detective Beckett, this is Mister Castle, we need to ask you a few questions regarding Professor Ignaz Holtzmann." Beckett announced herself.

"Now I know how I knew your face, I saw it on a book." Penny said, the coin dropping.

"Always great to meet a fan." Rick smiled smugly.

"No, not a fan really. Never read one of your books." Penny shrugged, causing Kate to smile to herself as his face fell.

"What was your relationship with the victim?" Kate asked.

"He was my thesis adviser at Princeton. Without him, I might have not become an experimental physicist." Leonard replied.

"Did you ever argue about things?"

"Of course we did but can we please get your suspicion out of the way that I killed Ignaz." Leonard started. "We both know I'm innocent, since I have a pretty good alibi."

"What makes you so sure your alibi is solid?"

"Because I have around two hundred people who can vouch that I was in a lecture hall until four-thirty and it's even on Youtube." Leonard replied.

"You were seen arguing with him." Kate stated.

"Again, that wasn't an argument." Leonard sighed.

"Really, then why was he flailing his arms around?" Kate asked.

"It's the way he gesticulated when he got excited, I think it's some Czech thing."

"What were you talking about?"

"Our work. Or, to be more exact, his work."

"What did he work on?" Rick asked.

"Haven't you seen the news last week?" Penny asked back.

"Right, he was saying that he was about to unveil a car engine that ran on nothing but water and could circle the earth twice without refueling." Rick nodded.

"That would be quite the achievement." Kate said. "Something someone might kill for."

"Of course." Leonard nodded, not getting that Kate was trying to make him incriminate himself. "There are a lot of people out there who wouldn't want a technology like this to become available to everyone."

"I was saying this more in regards on its monetary worth, to be the maker of this engine." Kate added.

"Sure." Leonard shrugged. "But that's of no concern to me."

"Are you sure? Could be billions of dollars." Rick threw in.

"Yeah it could but you don't know me, so what do you know about how I think of money?" Leonard asked exasperated.

"You are Doctor Leonard Hofstadter, living and working at CalTech in Pasadena, California." Kate read from her file.

"Impressive." Rick interjected. "But come on, everyone likes money."

"Sure, who doesn't like money. But if making huge amounts of money was my goal in life, I wouldn't be working at CalTech. I would be in some private company, raking in the big bucks." Leonard shrugged. "I mean, I have a good life. I have a good job and beautiful wife. Why would I risk everything I have by killing a friend of mine who I supported with my capabilities to make his dream come true? I don't want to be super rich and Ignaz never wanted to either. He wanted to make the plans accessible for anyone, so everyone could build an engine that ran without fossil fuel."

"Very well, lets say you didn't kill him." Rick said, trying to get the argument out of its circle. "Who would have reason to do it?"

"Every leader of the fossil fuel industry. Every head of state of oil producing countries who make the bulk of their money with selling oil." Leonard replied. "How did he die?"

"Apparently, he was shot by a laser." Rick replied.

"What? I saw him on the floor, he had a big hole in his chest." Leonard was flabbergasted.

"A hole apparently made by a laser." Rick nodded.

"But that's impossible. No laser exists yet that could do that."

"You're pretty sure." Kate said.

"Of course. High energy laser research is my field. I know what lasers can do but I also know their limits."

"How so?" Rick asked.

"Let me show you." he said and grabbed in his pocket, producing a laser pointer. "This is a laser pointer. It's a very weak laser that's basically just light. It produces no heat at all and unlike in movies you actually can't see the laser beam, just the end when it hits an object, except you're pointing it through smoke."

"Alright." Rick nodded.

"Honey, can you give me that prism?" he asked Penny.

"Sure." she rummaged in her purse and produced a prism she had gotten earlier as a fancy.

"Now, look what happens to the endpoint, when I put a prism in front of it." he said and put the prism in front of the laser pointer, creating a paler but wider laser point on Rick's chest.

"So what, the killer used a prism to widen the beam?" Kate asked.

"A prism or something else." Leonard nodded. "Just so you know, I want to help with the investigation. I want to know what the killer used to make a wide beam lethal. Also, Ignaz was my friend."

"This isn't a game, I can't have a second civilian following my team around." Kate said resolutely.

"I have no interest in going out into the field. Also, if Ignaz was killed because of his project, I might be a target as well, even though I worked with him only peripherally."

"I'm sorry, but I can't help you with that. This is a police investigation and no matter how good your intentions, you won't be a part of it."

"Fine, then I will do what I can to figure it out myself." Leonard stated, crossing his arms.

"If you interfere with the investigation, you can be charged with obstruction of justice." Kate warned as Leonard stood up.

"I have no interest in your investigation other than who killed the man who was my friend and who I looked up to." Leonard clarified. "My interest is purely technical because I want to know how the killer managed to create a lethal, five inch wide laser beam."

"As long as your actions don't affect our investigation, you're free to do what you want." Kate nodded.

"Thanks." Leonard said. "Can I go into Ignaz's lab?"

"CSU is done with it but the cleanup crew might still be there."

"As long as they don't touch the lasers, it's okay. I might find out which one the killer used."

"Good luck." Kate said and dismissed him.

Leonard took Penny's hand and led her out of the precinct. He hailed a cab and they got into it, giving the driver the direction for Columbia university, where they were staying in one of the apartments on campus reserved for faculty. They got out and he walked down to the lab where his friend had been killed, stopping at the police tape that the cleanup crew apparently forgot to take off.

He ripped it in two and entered the lab, looking around with a sad look in his eyes. Penny noticed his body language and linked her arm through his, giving him silent support as he tried to process the fact that the man responsible for him becoming a doctor was gone. After a minute of composing himself, he moved towards one of the lasers and checked it.

"Leonard, do you really want to do this?" she asked.

"I have to." he answered. "I owe it to him."

She watched him as he mulled over the equipment, the time passing and the day turning to night. Leonard checked every piece of what looked, to Penny, like lasers, reading their usage logs and making notes a piece of paper he had produced from somewhere. But when he just sat there for ten minutes doing nothing, she had to do something to prevent him spiraling out of control.

"Sweetie, lets go." she said forcefully, taking his arm.

"No, I need to work." he protested.

"What you need is a shower and sleep." she told him and pulled him out of the lab, closing the door behind her.

They walked across the campus to the residence where their apartment was located and entered it, walking up the two flights of stairs to their floor and through the door. She pushed him into the bathroom and undressed him, doing the same with herself and taking a shower with him, mostly to give him comfort but also to use her body to distract him from his glum.

After showering and teeth brushing, they simply got into bed and she let him hold her tight, knowing that he needed the comfort of knowing that she was there. But even though they didn't plan it, both fell asleep a few minutes later, Leonard dreaming of his mentor and the good times. Unfortunately, a few hours later, both felt each other being pulled apart and woke up, giving voice to their shock before someone pushed chloroform-soaked cloth was pushed into their faces.

The last thing Penny saw were four men, one of them hoisting the unconscious form of her husband over his shoulder. Then everything went dark. She didn't feel how she was also thrown over a shoulder and carried out of the building.

* * *

Kate and Rick walked into the bullpen, coffee cups in hand and ready to work. She hoped that their efforts with the security tapes of the lab building would give them some information on the killer since, so far, they didn't even know if it was a man or woman who did it. Ryan, in his usual fashion, was already hard at work, sitting at his desk with the surveillance video running while he did internet searches in between.

"Ryan, you got anything?" Kate asked.

"Yes and no." Ryan sighed and Kate gave him a look that prompted him to continue. "Apart from the victim, we have one guy walking into and out of the lab inside the time of death window. He's not even trying to hide his face." he explained and pointed at the screen.

"So what's the problem?" Rick asked.

"The man is a ghost." Ryan sighed. "I ran his face through every database we have access to and came up empty. I even tried the Interpol database and the only thing I got was a profile page with everything saying unknown. No known name, no age, no address."

"Dammit." Kate cursed. "So, basically we have our killer but no idea who he is."

"We're checking street cam footage for his face but we don't have the resources to do a live surveillance of every camera in New York." Ryan told them.

"We do have another source." Rick pointed out in low tones. "One that has gotten us the identity of a masked man before, using only the left eye that was visible."

"Who are we talking about?" Ryan asked.

"Our friend." Kate nodded. "But how can we send him a picture if we only have the number of a burner phone?"

"I'll try." Rick said and took out his phone where he has noted down the number into his editor.

 **Need help. Killer completely unknown, murdered scientist who might have saved the world (no joke). No mask, just no information. We have pictures.**

Rick sent the message and the group waited, Esposito joining them while they did. After ten minutes, Rick's phone buzzed with a message, the answer containing only an email address and the note that this particular contact would be gone after this exchange. Kate sent the picture of their killer and the Interpol picture and the group waited again, this time for a longer period of time until Rick's phone buzzed again with a message he read out loud.

"Name of the killer is Francois De Lande, age forty-one. French National. Professional hitman. Master engineer and inventor. Very versed in using various technology to kill his victims."

"Who got those information?" Esposito asked.

"Our friend." Kate replied, making a finger motion across her throat.

"Ah, him." Esposito nodded as Ryan's phone rang, who excused himself to take the call.

"Alright, we now have a name to go on. Although that doesn't really help us find him.

"Beckett, we got a problem." Ryan said as he came back.

"What's going on?" she asked.

"The Hofstadters are gone."

"What do you mean, they are gone?" Rick asked, standing up.

"Apparently, they were taken last night. The night watchman at the gate was found bound and gagged and some of the staff who also live up there called the campus police this morning, saying their door had been pried open." Ryan explained.

"Dammit." Kate cursed. "Call the university, have them send over the surveillance tapes of the residence unit and outside areas, maybe we'll see a car or a person."

"On it." Ryan nodded and walked back to his desk to use the phone.

"Why take them?" Kate asked into the air.

"Doctor Hofstadter said it himself, remember? Whoever did this might think that he too has knowledge of that engine project and wants to tie up loose ends." Rick replied.

"But why kidnap them? Why not outright kill them?"

"Could you be sure that they haven't something in writing stored somewhere?"

"Right, that's possible." Kate admitted.

"We got the surveillance." Ryan proclaimed.

"Anything good?" Rick asked as they walked into the tech room where Tori was busy checking the video.

"There's a white van parked two hundred feet away from the gate and four masked men exited it." Ryan described as they watched the video. "And look at them knocking out the guy at the gate before heading in and exiting ten minutes later with two seemingly unconscious bodies."

"Can we get a license plate?" Rick inquired.

"We can, we did and we already ran it." Tori told him. "But it's defunct."

"We're trying to follow them by using the street cams on their route. Hopefully, we find out where they were heading, then we might find their place of operations."

"Do what you can, they have two hostages they will surely kill when they get what they want."

For the next few hours, the group all checked the video, deciding that several pairs of eyes had the most change not to miss something important and they watched as the van snaked its way through the nightly New York traffic. Unfortunately, they lost it when it took a right turn into an old warehouse district.

"Dammit." Kate cursed. "Searching that area would take way too long and most likely tip them off."

"But how else can we narrow it down?" Ryan asked. "Only a handful of the three dozen warehouses are currently in use."

"Tori, do you have access to the energy grid?" Rick asked.

"No, why?"

"Well, we know which warehouses are in use and those draw energy from the grid. Every other warehouse should draw nothing. So, could we check if one of those empty ones are drawing power? Even if it's only a small amount, like lights and maybe a few computers, it should be noticeable."

"I'll contact the power company and ask." Ryan said and walked to his desk again to make the call.

"Esposito, get an ESU team ready, we'll go in as soon as we have an address." Kate ordered.

"Right." the latino nodded and also made the call.

"Got something." Ryan called over after twenty minutes. "One of the empty warehouses at the shoreline is drawing power even though it's supposed to be empty. I called the district and they had a guard check it out, they found several cars in front of it, our white van one of them."

"Lets go." Kate said and the group headed out to hopefully save two lives and not recover two more corpses.

* * *

Penny tried not to cry as they were sitting on the chairs, where she was freezing due to her light attire, their wrists tied together with zip ties and their feet bound to the legs of the chairs. The two people guarding them played chess and were too invested into their game to even watch them, one of the two having his back to them while the other glanced over occasionally when his opponent thought about his next move.

She looked to her right and saw Leonard, zip tied as her, his head down. As if noticing her look, he turned his head and gave her a look that was in equal measure a declaration of love and an apology for getting her into this mess although he couldn't really be held responsible for anything of it. On her other side, she saw a tantalizing pair of scissors on a nearby wall table, so close yet so far out of reach.

When they had woken up after being knocked out with chloroform, Penny had vomited at first before managing to get a look at their captors. One of them was a poised man in fitting clothes who, despite his smaller appearance compared to the others, emanated an aura of menace and dread that had her shrink back in fear.

The guy had started questioning Leonard, hitting her husband whenever Leonard closed up. After a few minutes, they were dragged into the room they were currently sitting in and when one of the henchmen had begun to feel up Penny's legs, she had kicked him hard in the shin and received a slap in the face as well.

Luckily for her, the man in charge apparently was civilized enough to not want his guys abusing his hostages, at least it appeared that way. When the guy had protested, the boss had taken his gun and shot the man into the testicles, startling Penny with the sudden noise of the gunshot and repeating his order not to touch neither her nor Leonard without his permission and for what it was worth, Penny was grateful as they carried the wounded man out of the room. That had been several hours ago and since then, they were waiting for something to happen apart from their two guards playing chess.

One of their guards suddenly shouted checkmate, fist-pumping the air while the other groaned in defeat. She was scared out of her mind that they might try to find another way of entertaining themselves, one including her, though their boss, or at least the man in charge of this thing had made it perfectly and, very painfully to one of his crew, clear that she was not to be harmed in any way. As the loser set up the board again for another game, the phone of the winner rang, which led to a short conversation before he hung up again.

"Sorry buddy, boss needs me for something." winner-guy, who she thought was the one the boss called Miller, said.

"Ah come on, what am I supposed to do here?" loser-guy, who would be Johnson, complained.

"You'll find something." Miller winked and unlocked the door before opening it.

"What is there to find? There's nothing here except these two and I can't even do something with the chick since I don't want to lose my balls like Rodrick."

"Tough. I have to go, boss is waiting." winner-guy waved him off and left, closing the door and locking it behind him.

"I could play with you." Leonard prompted.

"What?" loser-guy asked doubtful.

"I know how to play chess."

The guy thought it over for a moment, as if contemplating the different outcomes of his actions of either be bored out of his mind or getting in trouble for freeing one of his captives just to pass the time. Apparently, the boredom was a worse idea than possible trouble, because the guy suddenly got up, pushed the empty chair on the other side of his table aside and then carried Leonard along with his chair to the table.

"Alright, lets play." Johnson prompted and made the first move.

"Uh, it's kinda hard to do with my hands tied behind my back." Leonard shrugged.

"Oh, wait. But don't do something stupid." Johnson chuckled and got up again, getting a new zip tie. He cut Leonard free and allowed him to roll his shoulders for a few seconds before tying his hands again, only this time in front of his body. "Alright, lets play."

"On one more condition." Leonard stopped him again.

"What?" Johnson asked exasperated.

"Could you push my wife closer to the radiator please? I noticed before that her hands are already turning blue from the low temperatures here."

"Fine." Johnson huffed and got up again, moving Penny with her chair so that her hands were almost touching the radiator.

Nodding a thank you to Leonard, who winked conspiratorially back at her when Johnson wasn't looking, she felt her hands warm up and starting to tingle. Leonard finally made his own first move and the two started playing, with Leonard thinking, or at least appearing to, about his moves. Having played chess with him before, she noticed that he wasn't really playing to win but his moves were something done by someone playing for time, though she had no idea why.

As she rolled her wrists to try to get some circulation back to her hands, she noticed that she was able to pull them apart slightly. Suddenly, she knew why Leonard had wanted her against the radiator, since heat made plastic more elastic, aiding in her escape. Contorting her hands while keeping as quite as possible, she managed to wriggle her left thumb out of the plastic and then it was easy to free her hands. Catching the zip tie before it could fall down and make a sound, she avoided rolling her shoulders like Leonard to prevent them from cracking and looked around, seeing the scissors that had seemed too far away in reach of her right arm now, thanks to her repositioning, courtesy of Leonard's prompt.

She moved slowly and grabbed the scissors, cutting slowly to avoid sounds and was soon free. Standing up, she took one of the loose bricks she had noticed upon their entry and tiptoed to their guardian who was still immersed into his game with his back turned to her. Leonard, for his part, managed not to look behind Johnson to not give her away and with a mighty swing, she let the brick connect with Johnson's head, causing the big man to crumble from his chair to the floor.

She quickly got the scissors and cut Leonard free, who then took a few more zip ties and joined Penny at Johnson's prone form, where they proceeded to tie his wrists and ankles together before bending his knees and using another set of ties to connect the other two zips together, completely immobilizing the guy and for good measure, they used a piece of his shirt to gag him.

"Are you okay?" he asked her, hugging her tight.

"I'm fine." she said teary and kissed him. "That was a smart move with the radiator."

"I'm glad it worked."

"We still have to get out of here." Penny said. "We have no idea where we are or even if the others are on the other side of that door."

"No time like the present to test it." Leonard sighed and looked around for a key. "Damn, he doesn't have a key."

"Maybe I can pick the lock." Penny suggested.

"How?" Leonard asked.

"They didn't take my hair clip out, maybe my wild youth comes in handy now." she replied and bent down at the lock.

"You picked locks as a teenager?"

"My sister taught me. Came in handy when we wanted a drink from my dad's whiskey cabinet." she shrugged with a smile and continued.

For several minutes, she tried unsuccessfully to open the lock, the evolution in them far outweighing her outmoded skills at picking them. Her stubbornness winning over, she refused to concede defeat and tried again and again to set the tumblers into the correct position but before she could attempt her fiftieth try, the door unlocked audible and swung open, hitting her in the head and pushing her backwards.

Any pain she felt was immediately washed away when she heard the deafening boom of a gunshot and saw a fountain of blood shooting away from Leonard's left temple as he collapsed to the ground. For what appeared to be an eternity, she couldn't move a muscle as she watched him fall to the ground, hitting it with a meaty thud and coming to rest with his glasses askew and his eyes closed.

She let out a bloodcurdling scream of pure anguish as a pool of blood appeared from below his head, causing her body to react and try to reach him. She didn't even see her captor as he swung his gun towards her and tightened his finger around the trigger and was only brought back to some measure of her senses when multiple gunshots rang out and their captor danced like a string pupped before collapsing himself with several smoking holes in his back.

"Leonard, no!" she cried in soul wrenching agony and tried to turn him around when she was roughly shoved away by a steely-blue eyed detective who took her position next to him.

"WE NEED A MEDIC NOW!" Ryan yelled on top of his lungs as more people piled into the room, most of them wearing helmets to their uniforms and carrying assault rifles.

"Do something please!" Penny shouted, tears flowing freely and trying to get out of the grip of the latino detective, who held her back as the units medic knelt down by Leonard and turned him fully on his side before checking his pulse.

"He's alive!" the man proclaimed and used a disinfecting wipe to clean the blood from Leonard's face who began twitching.

"Ow, that hurts." Penny heard the voice of her soulmate, which almost made her collapse in relief had she not been held by the other detective, who let her go as soon as she was steady again.

"You're alive." she sobbed and ran over to him, hugging him despite fresh blood running down his face while the medic kept his upper body upright with his leg to check on his head. "How? I saw the guy shooting you."

"Looks like the bullet only grazed his temple." the medic explained. "The fall most likely caused a deep laceration, hence all the blood. A few stitches and all he will have left is a scar and a headache."

Penny refrained from hugging Leonard again as the medic helped him to his feet but she made sure never to leave his side and have her arm linked with his as they walked outside to the waiting ambulance. There, Leonard was sat on the gurney and the attending paramedic looked him over before cleaning the wound and using some ice spray to numb the area so he could stitch it together in a few swings of the needle.

"Are you okay?" Kate asked upon joining them.

"Apart from some cuts and bruises, yes." Penny nodded. "How did you find us?"

"Good old police work. We used street cam footage to trace the route of the van you were taken in until it disappeared here in the area and then we checked which building was drawing power."

"Smart." Leonard nodded. "Thank you detective."

"You're welcome."

"Did you find out who the guy worked for?" Penny asked.

"Not yet, but we hope to find some form of either paper work or digital trail." Kate replied.

"What of the device?" Leonard added.

"What device?"

"The device he used to kill Ignaz with. The one turning a laser into a wide and deadly beam."

"Since we have no idea what to look for, I would say no." Kate shook her head.

"Mind if I take a look?" Leonard asked.

"Feel free when CSU is done with the place."

They waited for almost an hour, both wrapped in police jackets so they could get warm again after sitting for hours in a cold and damp room, until the CSU team finished up and brought everything out and placed it into their van. Leonard walked over and, after Esposito cleared him, started looking through the various evidence bags to see if he could find whatever he was looking for.

"Any luck?" Rick asked, who had waited in Kate's car while the operation went down, against his usual habit.

"No, not so far... wait." Leonard said, grabbing one of the bags that held something looking like a dark lens. "This could be it."

"Is that a lens?" Rick asked. "Is that the murder weapon?"

"Is what the murder weapon?" the voice of Kate interrupted them.

"A focus lens." Leonard nodded. "Too bad it's broken."

"The lens looks fine, no cracks." Rick pointed out.

"True, but the lens alone can't turn a thin laser into a five inch beam." Leonard explained, holding it up. "At the back was something else but it broke apart. My guess is that whatever was in there was the focusing part."

"That's a bummer." Penny said, hugging her husband from behind.

"Not entirely." Leonard countered. "Detective, if you are done with this, I would really like to have this."

"Why?" Kate asked. "I thought it was broken."

"True, but the lens alone is a marvel. It's not glass or even crystal but something else. A material able to bear the strain of shooting a five inch laser beam through it without melting."

"Obsidian maybe?" Penny asked.

"Could be. Although obsidian is usually darker and also rather brittle." Leonard told her.

"Obsidian?" Kate asked.

"Yes, also known as volcanic glass." Rick replied. "It's created when... never mind." he broke off when seeing his wife's look.

"Well, we will keep it in evidence for a while until we can find out who the person behind all that is. If we can find out." Kate shrugged. "Otherwise, you can have it."

"Thanks." Leonard smiled and wrote his name on the bag with a sharpie, causing Penny to smile. "Can we go now?"

"Sure. I'll have a unit drive you back to the university." Kate nodded and waved an officer over.

Leonard and Penny walked with the officer and got into his car, letting the man drive the long way to Columbia staying silent the entire drive, letting their hands to the talking in holding each other. The first thing they would need is a shower, Leonard especially since he still had some dried blood on his skin. Half an hour later, they were walking across the campus, getting looks from the few students who were still there but luckily, none asked a question.

"You know, I had fun." Penny said, trying to lighten the mood.

"You're kidding." he squinted his eyes at her.

"Well, you did say a week in New York will be an adventure. And what's adventurous than getting kidnapped."

"A few things come to mind." he huffed but smiled nonetheless. "I love you."

"I love you too." she said. "You know, when I saw you fall after you got shot, I thought someone had ripped my heart out."

"Felt really strange, like a sting. Didn't feel anything else after I hit the ground."

"I'm so glad you're okay."

"Hey, you realize, this is my second gunshot wound." he pointed out, reminding her of the time he shot himself in the foot. "You're married to a badass."

"Yeah, you're a certified tough guy." she laughed.

Inwardly, she still worried about the implications of what had happened to them. The guy responsible might be dead but the people behind him were still out there. On the other hand, Leonard's research was something different than his dead friend's, so the danger should be negligible. For now she decided to enjoy being his wife, the events of the day having her made aware that every second was precious and their life together could end in the next second.

But for now, they would go to sleep and tomorrow, go back to Pasadena to their regular life and friends.

* * *

 **Well, there you have it. My (first, depending on the response) attempt at a crossover of these two universes.**

 **Tell me what you think. But be gentle ;)**

 **Review please :)**


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